High capacitance electrode and methods of producing same

Abstract

The present invention provides improved cathodes and methods for producing such cathodes for ultimate use in conjunction with valve metal capacitors. A family of titanium carbide cathodes according to the present invention can be produced so that they inhabit a pre-existing metallic surface such as an inner surface of a titanium casing adjacent but insulated from direct electrical communication from an anode. Foil-type valve metal anodes as well as porous valve metal anodes formed from metallic powders may be used in conjunction with the titanium cathodes of the present invention.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present provisional patent application claims the benefit of prior provisional application Ser. No. 60 / 514,371 filed Oct. 23, 2003 having common title, provisional U.S. patent application Ser. No. 60 / 514,372 filed on 23 Oct. 2003 and entitled, “METHODS OF PRODUCING CARBON LAYERS ON TITANIUM METAL,” and relates to non-provisional U.S. patent application Ser. No. 10 / 692,649 filed 23 Oct. 2003 and entitled, “ADVANCED VALVE METAL ANODES WITH COMPLEX INTERIOR AND SURFACE FEATURES AND METHODS FOR PROCESSING SAME,” the contents of each said prior application is hereby incorporated by reference herein.FIELD OF THE INVENTION[0002]The present invention generally relates to improved capacitors; in particular, the present invention provides cathodes for use with valve metal anodes and methods for fabricating such cathodes to produce high energy density capacitors. More particularly, such cathodes find use in high voltage capacitors incorporated i...

AI Technical Summary

Benefits of technology

The present invention provides improved cathodes and methods for producing them for use in valve metal capacitors, particularly those used in implantable cardiac devices. The cathodes are produced by depositing a layer of carbon onto a titanium substrate, which can be done using various techniques such as chemical vapor deposition or plating. The carbon layer can be very thin, and it is believed that a small amount of carbon remains on the titanium surface, which helps to maintain the capacitor's performance. The resulting cathodes have a high degree of fault tolerance, meaning they can still operate effectively even if some of the carbon is removed. The invention also includes a method for depositing a porous valve metal anode onto a titanium casing for use in capacitors. Overall, the invention provides a novel and non-obvious way to achieve the specific capacitance and fault tolerance requirements of valve metal capacitors.

Problems solved by technology

The battery(s) and high voltage capacitor(s) used to provide and accumulate the energy required for the effective cardioversion / defibrillation therapy have historically been relatively bulky and expensive.

In addition, it is believed that the voltage drop across all double layer regions must remain at or about one volt, otherwise gases may be formed via electrolysis (a potentially serious problem for an IMD).

The mechanism for such continued operation is not fully understood at this time; however, it is likely that the carbonaceous material remaining at the titanium-carbon interface consists mostly of titanium carbide material, since the above-mentioned processing involves a vacuum heat treatment step.

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